Chemical Bonding

Why? To achieve stability (happiness) Lower energy level 8 electrons –react so as to achieve the valence level configuration of

NEAREST inert gas

How? 1. Ionic Bond:

◦ Transfer of electrons from Metal (low IE/EN) to non-metal (High IE/EN)◦ Larger difference in IE/EN

2. Covalent Bond: between NON-metals b/w items with similar IE/EN (small difference) Due to SHARING of electrons

2. Covalent Bond: between NON-metals b/w items with similar IE/EN (small difference) Due to SHARING of electrons

* In a given covalent bond each element contributes 1 electron to the pair

shared**BOND FORMATION: due to an overlap of

atomic orbitals on the valence level* Identical Bonds: identical in every way,

strength, length etc

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Bonding cont’d

Sigma Bonds: the first bond formed between two atoms

- it will use hybrid orbitalsPi Bond (π bond): the second/third bond

formed between two atoms

PURE ‘P’ for PI bonds

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So..... Why do we care???

So..... Why do we care???

Knowing # of bonds and # of lone pairs allows us to determine shape of a molecule and then in term helps to determine polarity!! Woot woot

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VSEPR Theory

Valence Shell Electron Pair Repulsion TheoryElectron pairs around the atom place themselves

AS FAR APART as possible (Bonding or nonbonding lone pairs)

Determines geometry of a molecule based on Lewis structures

Lone pairs on the central atom have basically the same affect as a bonded pair of e-

Electron Pair Geometry

3 e- pairs 4 e- pairs

5 e- pairs6 e- pairs

Variations on Trigonal Planar

seesaw

Polarity – Bonds and Molecules

Bond Types:1. Ionic: transfer of electrons2. Covalent: equal sharing of e- pair3. Polar Covalent: unequal sharing of e- pair, creates dipoles (slight

charges), determined by ΔEN of the elements

Determining Polaritysmartboard

Classify the following as polar or nonpolar A) BeI2 b) CF4

c) CH2O d) CO2

e) BF2Cl f) CH3Clg) SF6 h) SCl2  

Intermolecular Forces

Two types of forces1. Intramolecular: within a molecule

(ionic/covalent bonds)2. Intermolecular: between molecules

Wrap up Video Intermolecular Forces

Work: pg. 260

◦#1)a,b,f 2) a,d 3) b,c 4. a) b) 5) think about it

Pg. 264 #9) a,d 11

Pg. 266 #5, 7 – great test questions